I have a map that I am making that is shown at a 1:200' scale. If I choose to zoom into a different area of the map, lets say to a 1:72' scale, how do I keep my scale bar from resizing to a point where it no longer displays a standard of one inch. My whole goal is to have a double alternating scale bar that can always be measured at 1 inch for the first segment of the bar.

Mapping Center Answer:

To restate the goal, you want a scale bar that does not change size when you change the associated data frame's scale. That's the default option*--once you've added a scale bar to your map's layout, open it's properties and on the first tab, Scale and Units, you'll the the option, about half way down, called "When resizing".

To get the exactly one inch requirement, use the "Number of divisions" value (second property above "When Resizing") and let's say for example that's 4. Go to the Size and Position tab and set the Width to be 4 inches, i.e., match the value of your number of divisions.

*The behavior of the software is such that if you change your data frame's extent/scale, the scale bar will change size--mostly because of ArcMap rounding the division length value for the purpose of presenting easily readable--it's bad form to change the value to something like 1.23324 miles to the inch. So, you will need to use the Size and Position tab each time you change scales, prior to printing or exporting.

That solution is kind of a big hassle... posted by Travis Bugg on Oct 6 2014 12:03PM

Has any improvement been made on this in the last 5 years? I, too have to make maps with strict 1 in = xx meters scale bars. I can understand rounding, but arcmap rounds 64 m to the inch down to four 10 m divisions! It will not, under any circumstance round to 15! I'd be fine with just rounding to whole numbers. Anyway, the solution is incompatible with data driven pages, as you must export out each map individually after adjusting the scale bar. This isn't an option with map sets in the hundreds.